More intense storms are expected to hit New York City in the coming years. But the hundred-year-old sewer system already can’t keep up. So when it rains, sewage overflows into streets and waterways. One area hit the hardest is the Gowanus neighborhood in Brooklyn, where people are trying new ways to fight flooding. Cassandra Basler tells us how small gardens built into sidewalks may help collect some of the runoff.

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The Gowanus Canal. This murky, gray-green waterway makes the E-P-A’s list of most polluted sites in the country. And when it comes to flooding Build It Green, a non-profit that sells salvaged materials from old buildings, is in a bad spot.

BIRNBAUM: We are in the Gowanus Neighborhood, the lowest point on 9th Street. Flood Zone A.

Matt Birnbaum is the retail manager at Build It Green. Here, even light rain can cause problems.

BIRNBAUM: Yeah. Anytime we get more than a half-inch to a three-quarter inches of rain in a short period of time over here… the sewer systems become overwhelmed.

He says to hold back water…the landlord had to install two $10,000 dollar aluminum floodgates… seawalls on the sidewalk. But the runoff still makes a mess of the street…and the canal.

BIRNBAUM: I was standing on top of these floodgates yesterday. I can show you videos of it. We had about a foot and a half of water here yesterday so it wasn’t so bad. But this whole street was filled with water. You couldn’t see the concrete.

DIEGEL: The rats will balloon up like white soccer balls and there is a very special sewer scum that comes in when there’s a full flush out.

That’s Eymund Diegel from the Gowanus Canal Canoe Club. He rows with volunteers who test the canal’s water quality. He recently went to a meeting with the City Department of Environmental Protection. There, officials said updating the sewer system would cost billions of dollars—too much. Instead, the city will install a few high-capacity pipes and use gardens to capture some of the runoff. They plan to build more curbside gardens, called bioswales.

Three blocks away from Build it Green in Gowanus, LaToya Anderson is showing off a garden that’s built into the sidewalk.

ANDERSON: What we’re looking at right now is a structure that’s about five feet by 20 feet. It’s recessed further in the ground below the normal concrete street level and it’s filled with a mixture of soil and sand.

It’s called a bioswale. But it looks like a patch of prairie plants growing in a neat cement rectangle between the sidewalk and the street. It’s like a tree plot, but three times the size. It collects water from the road through a downward slope in the curb. To keep the dirt from washing away, volunteers planted hardy low-maintenance grasses and wild flowers.

ANDERSON: They are able to absorb a lot of water very quickly.

Anderson works for the Gowanus Canal Conservancy that installed these bioswales. The gardens can soak up an inch of storm water, which might be enough to prevent sewage overflow.

Matt Birnbaum says the city’s plan to install two thousand bioswales across the boroughs is a start, but more will be needed.

BIRNBAUM: It will have some impact surely… but if you think about what the total square footage of that is… It’s kind of like peanuts, right?

This winter the parks department will begin installing a hundred of these gardens in Gowanus. Some will be planted in time to catch the snow melt.